The majority of cable television content providers distribute their signals in a respective transport stream by digitizing the signals using an encoding format such as MPEG-2 (Motion Picture Experts Group-2). Encoding in accordance with MPEG-2 TS (MPEG-2 Transport Stream) works well for cable television because it is a broadcast service. MPEG-2 TS encoding does not include specific device delivery address information and thus affords higher transport efficiency.
Several modes can be used to transfer the MPEG-2 TS to one or more end users in a current state of the art shared cable network system. In one mode, the MPEG-2 TS is Quadrature Amplitude Modulated (QAM) at a base-band frequency and then Amplitude Modulated (AM) onto a laser signal for fiber optic transmission to a distribution hub in a cable network environment. The distribution hub forwards the signal as an AM laser signal to a distribution node. The receiving distribution node converts the laser signal back to RF at a particular frequency and then combines it with other signals for final transmission over a coaxial cable to the end users in the cable network environment.
In more advanced systems, the MPEG-2 TS is IP (Interest Protocol) encapsulated and sent to the hub using the User Datagram Protocol (UDP). UDP is beneficial because it is a “best effort” delivery protocol. Thus, no overhead is incurred with retransmissions due to lost packets.
In accordance with broadcast technology, a common encoded signal can be transmitted over the coaxial cable to all of the end subscribers in a service group. Thus, if a television station is encoded at a bit rate of 10 M bits per second (Mbps), then 10 Mbps of the transport pipe—for example, fiber optic link, coaxial cable, etc—is consumed for all subscribers.
U.S. Pat. No. 6,233,389 issued to Barton describes a mechanism in which a television signal is digitized and stored to a disk drive. The format of a digital signal is described in that patent as an MPEG-2 formatted signal. Receipt and storage of an MPEG-2 signal in a disk drive is convenient in current cable systems because, as discussed above, cable systems currently use an MPEG-2 TS format for distributing video. To record one of these signals in a disk drive, the system simply has to receive the signal, decrypt it if necessary, re-encrypt it using a local encryption, and then write the content to the disk drive or other storage media.
At issue is the finite storage capacity of a disk drive. That is, the disk drive eventually fills up with so much data that no more content can be stored in the disk drive. Encoding in accordance with the MPEG-2 standard is not the most efficient currently available encoding mechanism. Encoding in accordance with MPEG-4, section 10, is much more efficient because the MPEG-4 provides a higher degree of compression, without a substantial loss of quality.
New DVRs (Digital Video Recorders) incorporate a mechanism for un-encrypting (or decrypting) the content on the disk drive, re-encoding of the content into a format useable by a remote storage or playback device, application of a Digital Rights Management technology associated with an remote storage or playback device, and then transfer of the newly encoded content to a remote location such as a target device.
The majority of remote storage/playback devices now use MPEG-4 as a video encoding format. Soon, most portable devices will utilize the HEVC H.265 encoded format. Thus, the new digital video recorders incorporate special circuitry and/or software that can rapidly convert MPEG-2 TS encoded video to MPEG-4 or HEVC H.265 encoded video.